Dye and dyeing



Patented Nov. 8, 1932 UNITED STATES PATENT orr cs DAVID ALEXANDER WHYTEFAIRWEATHER, OF GRANGEMO'UTH, ANIJ.JOHN THOMAS,

013 KING-ARTE, POLMONT, SCOTLAND, ASSIGNORS TO IMPERIAL CHEMICAL INDUS-TRIES LTD., A CORPORATION OF GREAT BRITAIN DYE AND DYEING No Drawing.Application filed December 9, I930, SerialNo. 501,130, and in GreatBritain December 9, 1929.

It is an object of theinvention to provide improved or modifiedprocesses for the development of such esters.

We have observed that the development of estersof this type appears tobe in part a reversible reaction, and our invention consists in asuitable adjustment of this reversible reaction so as to facilitate thedevelopment of the colour or to prevent over oxidation. We achieve thisresult, for example,

in the case of development with ferric salts by the addition of a littleferrous salt or by the addition of salts of weak acids capable offorming double salts with the ferric salt present. In the case ofdevelopment with copper salts, in which it is probable that the coppersalt is converted into cuprous salt, acid and oxygen (the oxygen beingutilized in developing the ester), we achieve this same result byreducing the concentration of acid originally present.

In developing dyeings of the esters of reduced vat dyestuffs usingferric sulphate we have found that the addition of ferrous sulphate isof great advantage, for instance, uslng ferric sulpiiate alone it isvery easy to obtain oVer-oxi tion, particularly with certain dyestuffs,for example, those belonging to the indanthrone'class.

By the use of ferrous sulphate it is possible to easily avoid anyover-oxidation. This result is very unexpected, since the addition of areducing agent would not be expected to have any effect on thedeveloping process.

One special advantage of this addition of ferrous sulphate is that it ispossible to regulate the strength of the oxidizing agent with precisionto suit any particular dyestufi by varying the relative proportions offerric and ferrous sulphate. The oxidation is preferably carried out inthe presence of acid.

Instead of using ferric sulphate and ferrous sulphate, ferric chlorideand ferrous chloride or other pairs of ferric and ferrous salts may beused. 7

It is possible that the beneficial effect of the ferrous salt is due tothe fact that the reduction of a ferric to a ferrous salt is areversible reaction.

Instead of using pairs'of salts with the same acid, such as ferricsulphate and ferrous su'lphate it is possible to use ferric and ferroussalts of different acids for instance, ferric chloride and ferroussulphate. Using ferric sulphate and ferrous sulphate and acidulating,sulphuric acid forms a convenient acid. With ferric'chloride and ferroussulphate, hydrochloric acid forms a convenient acid. Salt may be addedin addition.

It is possible to omit addition of a ferric salt altogether, and form itin situ, it being practicable, for example, to work with ferroussulphate and sulphuric acid in the presence of air, but for large-scaleoperations development under these circumstances may not be suflicientlyfast.

Another method of developing a ferric salt is to use a ferrous salt inconj unetion with an oxidizing agent, for example, a nitrite orpersulphate and in these cases a small quantity of the additionaloxidizing agent will sometimes be found sufli'cient.

It is known to develop esters of reduced vat dyestuffs and similarsubstances by the use of copper salts in acid solutions.

One of the great advantages of the use of copper salts in thisconnection is the wide range of applicability of the copper salts andthe fact that it is easy to carry out the oxidation withoutover-development.

The use of acid is common to nearly all methods of developing esters ofreduced vat dyestuffs but we have discovered that reducing'theconcentration of acid in developing with copper salts increases insteadof reduces the developing power; thus, a solution of cupric chloride isa stronger developing agent than a solution of cupric chloridecontaining hydrochloric acid. The actual strength of the developingagent can therefore bevaried and controlled by altering the strength ofthe acid. I

This phenomenal-result has the advantages that it is possible toeliminate or to reduce the concentration of the acid and also thatdevelopment can be made to take place more rapidly. In carrying out thispart of the invcntion cupric chloride may be used, or alternativelycopper sulphate'with the addition of sodium chloride.

The explanation of the phenomenon is probably to be found in the factthat the reduction of cupric salts, to give cuprous salts, acid, andoxygen, is a reversible reaction.

When using ferric salts as developing agents for the ester salts ofreduced vat-dyestufi's the addition of salts of weak acids which willform double salts with the ferric salt presents certain advantages.

As is known in using ferric salts, particularly with some dyestufi'swhich are easily over-oxidized, over-development is liable to takeplace.

The foregoing method however is of special use in avoidingover-oxidation, whilst the use of double salts obtained from ferricsalts and salts of strong acids is not of the same advantage, since withthese the liability to overoxidation still exists.

The present invention, therefore, includes theuse of double salts in themanner which is mentioned, preferably in the presence of a smallquantity of acid.

The invention is further illustrated by the following examples in whichthe parts are parts by weight.

Example 1 curs even if the development is carried on for over 10minutes, and a pure bright blue shade results.

Example 2 In place of the ferricsulphate used in Example 1 in a bathotherwise of the same composition, an equivalent quantity of anoxidizing agent such as per-sulphate, bichromate, &c., may be added,these probably oxidiz ing part of the ferrous sulphate to the ferricstate and so producing a bath pfv the same ,"oxidizing power as inExample 1;

Example 3 dyed with 4 per cent times its weight of the sulphuric estersalt of leuco indigo is developed in the following bath:-

Example4 7 Cotton cloth is padded with a 2 per cent solution of thetetra-sulphuric ester of leuco indanthrone and dried.

The yellow dyeing so obtained is developed in the bath specified inExample 3 for 10 minutes at 80 C. Blue dyeings of exceptional brightnessare thus produced, and the time of development and temperature may bevaried within wide limits without superoxidation to the yellow azineoccurring.

' If necessary 10 percent of sodium chloride or sulphate may be added tothe developing bath to prevent bleeding of the colour.

Example5 Cottoncloth padded witha 2 per cent solution of thetetra-sulphuric ester salt of leuco indanthrone is developed in bathcontaining 2 per cent hydrated ferrous sulphate, per cent hydratedferric sulphate may be considerably varied.

Examplefi In place of ferric sulphate in Examples and 5 an equivalentquantity of ferric chloride may be used.

Example 7' I and per cent sulphuric acid for 20 min- I 'utes at 50C. Thetime and temperature Cotton cloth is dyed with the ester salt of leucoBb2 :'Bz2 dimethoxydibenzanthrone' (caledon jade green) and the orangebrown dyeing is immersed either in the bath specified in Example 3 orthat of Example 5 in the cold for a few minutes.

Example 8 W001 dyed as in Example 1 is developed in a bath containing 40parts of' a 10 per cent solution of ferric chloride, 360 parts of a 2per cent solution of ammonium oxalate crystals, 55 parts of concentratedhydrochloric acid, and 160 parts of water, for 4 .minutes at 90 C.

' Exam plc 9 Cotton cloth padded as in Example 4 is immersed at 90 C. ina 2 per cent solution of crystalline cupric sulphate in water.Developmentproceeds rap dly and the dyeing may be lifted and rinsed inabout 5 minutes.

Example 10,

Wool dyed as in Example 1, is developed in an aqueous bath containing 2per cent ferric ammonium citrate and 0.2 per cent sulphuric acid, for30. minutes at 90 C.

Example 11 i The proportions of the constituents of a developercontaining ferrous sulphate may be considerably varied withoutappreciably altering the shade produced in the case of a dyeing with anindanthrene ester. A smaller quantity ;of ferrous sulphate than in theprevious examples is satisfactory when the fabric is of wool, employingthe following bath containing 2 parts hydrated ferric sulphate, 5 partshydrated ferrous sulphate and 5. parts sulphuric acid'in 1000 parts ofwater. Development may be carried on at 85 C. for 15-30 minutes.

Example 13 In place of ferrous sulphate in any of the previous examples,ferrous ammonium sulphate in proportionately larger quantity may beemployed. The development is somewhat retarded and a slightly longertime in the bath is usually necessary for the production of the correctshade.

V General The invention is not limited to sulphuric esters. V Y

The invention includes development of the dyestuflf in substance. Itincludes colouring generally, for instance, dyeing as well as printingand padding.

. As many apparently widely different embodiments of thisinvention maybe made without departing from the spirit and scope thereof, it is to beunderstood that we do not limit ourselves to the specific embodimentsthereof except as defined in-the appendedpatent claims.

We claim:

1. Process for the development of enolic leuco-ester salts of dyestuffsin the presence of a ferric salt characterized by the addition of anagent capable of influencing the reversible reaction which the ferricsalt under I goes during the development, said agent being a salt of'theclass consisting of ferrous salts and salts of weak acids capable offorming double salts with said ferric salts.

3. Process according to claim 1 in which i the added agent is a salt ofa weak acid which salt is capable of forming a double salt with I theferric salt.

4. Process according to claim 1 in which the development occurs inthepresence of ferric sulphate and the added agent is fer.- rous sulphate:p

5. Process according to claim 1 in which the added'agent is an ammoniumsalt of a weak acid. 6. Process according to claim 1 in which the addedagent is ammonium oxalate.

7. Process according to claim 1 in which there is present, in additionto the ferric salt, another developing agent.

8.Process according to claim 1 in which there is present, in addition tothe ferric salt, a sibstance capable of generating nitrous aci 9.Process according to claim 1 in which the ferric salt is generated insitu by oxidation of a ferrous salt.

10. Process according to claim 1 in which part of the ferric salt isgenerated in situ by oxidation of a ferrous salt.

11. Process according to claim lin which, in addition to a ferric saltas developer and a ferrous salt as agent for influencing the reversiblereaction, there-is also present another oxidizing agent.

12. Process according to claim 1 in which a small quantity of acid isalso present.

13. Process for the development of enolic leuco-ester salts of dyestuflsin the presence of ferric sulphate, ferrous sulphate, and sulphuricacid.

14. Process of a ferric salt, characterized by the employment of theferric salt in the form of a double ferric salt of a weak acid.

.15. Process according to claim 14 in which the double ferric salt usedis a ferric ammonium salt of an organic carboxylic acid.

16. Process according to claim 14 in which a small quantity of acid isalso present.

17. A process of developing enolic leucoester salts of dyestuffs whichcomprises immersing a fabric impregnated with said ester salts, in adeveloping bath comprising an oxidizing agent and a ferrous salt andefiecting the development of said dyestuffs.

18. The process of claim ,17 in which said oxidizing agent is aferricsalt.

In testimony'whcreof we aflix our signatures.

. DAVID ALEXANDER WHYTEFAIRWEATHER.

JOHN THOMAS.

for the development of enolic 'leuco-ester salts of dyestuffs in thepresence 2. Process according to claim 1 in which the added agent is aferrous salt.

CERTIFICATE OF CORRECTION.

Patent No. l, 886, 947. I s I November 8,1932.

DAVID ALEXANDER WHYTE FAIRWEATHER T -It is hereby certified that errorappears in the printed specification of the above numbered patentrequiring correction as follows: Page 2, line 95, after "in" insert thewords "an aqueous"; andline 109, for the syllable "BbZ" read "B22"; andthat the said Letters7Patent should be read with these correctionstherein that the same may conform to the record of the case in. thePatent Office.

Signed and sealed this 27th day of DecemberA. D. 1932.

' J. Moore, (Seal) Acting Commissioner of Patents.

